>50,000 years - The length of the day used for astronomical timekeeping reaches about 86,401 SI seconds due to lunar tides decelerating the Earth's rotation. Un

>50,000 years - The length of the day used for astronomical timekeeping reaches about 86,401 SI seconds due to lunar tides decelerating the Earth's rotation. Under the present-day timekeeping system, either a leap second would need to be added to the clock every single day, or else by then, in order to compensate, the length of the day would have had to have been officially lengthened by one SI second. I guess we have another annoying clock problem to work on once we get done fixing the Y2038 and Y10k bugs.